A wavelength division multiplexing (WDM) optical transmission technology has been known as one of optical communication techniques. In the WDM optical transmission technology, a route of an optical path having a predetermined wavelength multiplexed in the WDM light may be changed. A route change of an optical path may occur when a failure occurs in an optical path, or may occur according to a readjustment or an optimization of an optical WDM network.
Related techniques are disclosed in, for example, Japanese Laid-open Patent Publication No. 2003-069455 and Japanese Laid-Open Patent Publication No. 2011-004227.